Die casting apparatus



June 14, 1938. K. KUBO 2,120,333'

' DIE CASTING AQPPAR'ATUS Filed April 15, 1937 Patented June 14, i938 UNiT-ED STATES m cas'rnyo APPARATUS Kaname Kubo, Mitaka-mura, Kitatama-gun, Tokyo, Japan, assignor to Nihon Magnesium Kabushiki Kaisha, Tokyo, Japan Application April 15, 1937, Serial No. 137,134

In Japan June 3, 1936 1 Claim.

is forced with speed into the mold space by applying high pressure thereto and by expelling air from the mold space, whereby preventing the air in the mold from being confined and compressed in the mold space, so that superior prod-.

ucts of die casting can be obtained.

The accompanying drawing illustrates the apparatus according to this invention, in which:-

Fig. l is a vertical section through the apparatus, and Fig. 2 is a plan view thereof, one half being shown in section taken along line IIII of Fig. 1.

Referring to the drawing, a receptacle A containing molten metal is arranged in a suitable heating furnace l, and is heated by means of heavy oil or other suitable fuel. A fixed piston B is supported in said receptacle near its bottom by means of a bracket 2. A pressure applying cylinder C is open at the lower end, and it is adapted to slide upwardly and downwardly engaging with said piston B. The upper end of the cylinder C is provided with a molten metal transferring tube3, and by which it is supported on a bracket 4. Said tube 3 terminates within lower die D which is also supported by said bracket 4. The bracket 4 is slidably mounted at both ends on posts 5, and is supported by springs 6 wound around said posts 5. An upper die d cooperating with the lower die D is mounted on the central portion of an upper bracket I. Said upper die (I is provided with an air escape port 8 which is in communication with a controlling valve ID through a discharge pipe 9. -'Said controlling valve ID is adapted to move with the bracket 1 along the posts 5, and it is opened when a valve lever II is engaged with and actuated by a projection l2. The valve I is connect- 50 ed through a flexible pipe l3 to an evacuating pump or to a vacuum. tank (not shown). The bracket 1 carrying the upper die dis connected by means of a connecting rod I4 to a crank I5 of a drive shaft l6 having a pulley or hand wheel 11, whereby the bracket 1 is reciprocated.

Upon rotating the drive shaft US by the hand wheel I1, the bracket 1 is first lowered actuated by the crank l5 and the connecting rod 54, and the upper die d engages with the lower die D, as shown in Fig. 1. Whenthe upper die it is lowered farther, it presses the lower die D, and the latter moves down together with the bracket 4 along the posts 5, compressing the springs 6, whereby the cylinder C immersed in the molten metal in the receptacle A is moved downwardly in engagement with the piston B. Consequently, the molten metal confined in the cylinder C is subjected to pressure and is forced through the tube 3 into the mold space formed by the upper and lower dies. At the same time, the lever ll 7 of the controlling valve I0 is actuated by the projection i2, and said valve l0 opens to the vacuum pump or tank, whereby expelling air from the mold space.

With the heretofore employed apparatus for .die casting, even though the molten metal was supplied with an elevated pressure,there' was a disadvantage that the product of casting was porous and, in some cases, pores appeared on the surface of the casting, considerably injuring the appearance of the product. The greater the pressure of the molten metal, the greater the porosity of the product, due to the fact that more air is confined and compressed within the mold space without being given an opportunity for escaping. On the contrary, according to this invention, the pressure applying cylinder C is rapidly pressed down by the inertia of the downwardly moving upper died engaging the lower die D, the cylinder engaging with the piston B and applying high pressure tov the molten metal in-the cylinder, and at the same time the air in the mold space is expelled by automatically opening the controlling valve Ill, so that the molten metal is introduced into the evacuated mold space under high pressure,-without compressing the air therein.

Uponthe upward stroke of the upper and lower dies, the cylinder C and the lower die D are returned to the normal position by the action of the springs ,6, the cylinder C sucking in the molten metal for next use. Upon downward stroke of the cylinder C, excess amount of the molten metal in the cylinder escapes through the space between the piston B and the lower end of the cylinder C, so that the pressure of the molten metal is automatically regulated. During the upward movement of the dies, when they reach the position shown in Fig. 1, the lower die D stopsand the upper die d only moves farther, opening the mold for allowing the product to be discharged. The casting produced in the apparatus of this invention does not possess any porosity, having smooth surfaces, and it isshaped most accurately.

The invention is applicable to the casting of brass or iron as well as for casting of light metal.

What I claim is:-

In a die casting apparatus, a pair of recessed die members, forming, when closed, an intervening mold space, means for initially closing said members by the independent vertical movement of one of said members and for then moving both of said members conjointly, a recepspace, an exhaust controlling valve and means for automatically operating said valve on the downward movement of the die members. KANAME KUIBO. 

